# Inductor Design Problem

Joined Jun 12, 2023
3
An inductor of inductance 80mH, 500 A at 60 Hz needs to be designed. But my area product is coming too high. Probably because of VA rating. Due to this I can't find a suitable core that matches its Ap. Please help me with calculations of Ap. Is there something I am doing wrong? My voltage comes out to be 15kV approx. VA rating comes too high which enlarges the Ap value = (VAe4)/Bm*f*Ku*Kf*J. Also how to select appropriate J value (current density)?

#### crutschow

Joined Mar 14, 2008
33,318
500A is a bit much.
It would help if you stated what the purpose of this inductor is.

Joined Jun 12, 2023
3
500A is a bit much.
It would help if you stated what the purpose of this inductor is.
Its a design problem for my training.

Joined Jun 12, 2023
3

#### kubeek

Joined Sep 20, 2005
5,791
My guestimate is that 80mH 500A 60Hz inductor is going to be at least the size of a washing machine. Wouldn´t expect off the shelf cores to fit.

#### BobTPH

Joined Jun 5, 2013
8,062
Maybe if you bent some copper bus bar into a coil…

#### MisterBill2

Joined Jan 23, 2018
16,465
Such an inductor was actually built as part of a DC noise filter for a ground support system many years ago. What was used for the torroid core was a LARGE eye bolt that had a massive cross section and a five inch diameter center opening.
The challenge will be to have enough core material and cross section to avoid magnetic saturation. The wire can be about size 3/0, which is much larger diameter than #3 size wire.
If an eye bolt with that diameter is not available, a 3 inch diameter one might work, but it will need a single layer of fiberglass tape, and wire with teflon (or Kynar ) insulation. The VA rating is not the issue, it is the current versus the wire size.
An alternative could be a tape-wound core, which can be fabricated in any size.
What core material was suggested??

#### Ian0

Joined Aug 7, 2020
8,935
My guestimate is that 80mH 500A 60Hz inductor is going to be at least the size of a washing machine. Wouldn´t expect off the shelf cores to fit.
We have a 250kVA 3-phase UPS in stock at work. The output inductor (360A per phase) isn't quite as big as a washing machine! But it will be rather a lot heavier.

#### kubeek

Joined Sep 20, 2005
5,791
We have a 250kVA 3-phase UPS in stock at work. The output inductor (360A per phase) isn't quite as big as a washing machine! But it will be rather a lot heavier.
But does it have 80mH? That needs 15kV to get 500A through the impedance at 60Hz.

#### Ian0

Joined Aug 7, 2020
8,935
But does it have 80mH? That needs 15kV to get 500A through the impedance at 60Hz.
I was going to look, but I got busy. Hopefully, I'll remember tomorrow.

#### MisterBill2

Joined Jan 23, 2018
16,465
I think that I have seen such inductors at an outside power station. They indeed are large. But they are in series with high voltage lines to limit fault currents from lightning strikes and such. A few years back I asked the right person about that.
They also adjust phase shifts somehow.
So the individual to explain in more detail is a power distribution systems engineer. And that is not me.